It is extremely difficult to provide liquid personal wash compositions with sunscreen components or agents which sunscreen components may be readily deposited on the skin or other surface. One significant problem is that the sunscreen agents will generally be solubilized by the surfactant and, while they may be deposited during lathering, they will be removed by rinsing.
The art does teach use of certain cationic polymers to enhance deposition of sunscreen materials onto the hair and protect from harmful effects of sunlight. U.S. Pat. No., 5,186,928 to Birtwistle, for example, teaches use of a cationic derivative of polygalactomannan gum for such purpose. The level of sunscreen is never at such a high level, however, that the sunscreen will not solubilize in surfactant solution (column 2, lines 54-57). By contrast, sunscreens of the invention are used in concentrations above their solubility limit in the surfactant system in which they are used at least in part to ensure minimum levels of deposition.
EP Publication 552024 to Unilever is also concerned with enhancing deposition of cosmetic agents, including sunscreens. Here, an additional oil phase is added in order to reduce solubilization of the oil/sunscreen into the surfactant phase thereby allowing more sunscreen to be available for deposition upon rinsing. The subject invention, by contrast, does not rely on an oil carrier to enhance deposition (the oil is said to reduce solubility of component in surfactant phase and thus enhance deposition). Further the subject invention requires use of relatively high levels of cationic polymer to both enhance deposition of sunscreen (sunscreens being used at much higher levels than those used in U.S. Pat. No. 5,186,928 noted above) and increase SPF ("sun protection factor").
EP 313,303 (assigned to Procter & Gamble) discloses compositions comprising tocopherol sorbate (antioxidant) which may be used in combination with sunscreen agents. The compositions must also comprise anti-inflammatory agent and topical carrier. There is no recognition from this reference of using cationic polymer to enhance sunscreen deposition, particularly in formulations containing high amounts of sunscreen.
U.S. Pat. Nos. 4,701,321 and 4,933,174 to Bernstein teach method of using liquid detergent with sunscreen agent. The compositions contain only nonionic and amphoteric surfactants, unlike the cleansing compositions of the invention which must contain at least 5% anionic.
WO 99/13854 (assigned to Colgate) discloses a skin cleansing, sun protecting composition comprising (a) a sun protection hydrophobic agent; (b) a polar organic solvent less polar than water; (c) oil; and (d) cleansing effective amount of surfactant or mixture thereof wherein oil/polar solvent ratio is 1:4 to 1:0.8. In contrast to the aqueous systems of the subject invention, this is a non-aqueous system (see bottom of page 11).
Other references teach compositions which may contain surfactant, N-polymer and benefit agent (e.g., U.S. Pat. No. 4,948,576 to Verdiccio et al.; EP 117,135). These references fail to focus on sunscreens and/or to teach or suggest that sunscreens must be used in amounts beyond their solubility limit in the surfactant systems in which they are used; and that, when sunscreen is used in such large amounts, cationic polymer (at relatively large levels) both enhances deposition and SPF values.